A roll assembly for a rolling-mill stand typically comprises a pair of axis-defining, coaxial, and axially spaced journals, respective roll supports carried in the journals, rotatable therein about the axis, and having confronting annular surfaces centered on the axis, and a roll ring centered on the axis and engaged between the annular surfaces. The service-side support forms on the axis an axially extending passage and an extension axially fixed to the drive-side support extends with radial play through the passage so as to be able to pull the two supports axially toward each other and thereby axially compress the roll ring between the annular sufaces. The drive side of the roll stand, that is the housing parts carrying the drive-side journal is normally stationary, but the opposite service-side journal block and associated housing parts are normally displaceable so that they can be moved out of the way and the roll can be pulled for refinishing and/or replacement.
Such a system has the considerable advantage that the most wear-prone of the element, the ring, can be replaced. The supports riding in the journals can be used with rings of different sizes and can have a service life that is many times longer than the service life of the workpiece-engaging central ring.
Such roll assemblies are described in German patent document Nos. 1,140,535, 1,146,467, 1,602,086, and 132,726 and in U.S. Pat. No. 4,653,304. In these arrangements the two holder parts have axially confronting parts formed with interengaging teeth that rotationally couple them. These teeth have some axial play so that they do not impede clamping of the wear ring between the holding elements.
As a rule one or both of the holding elements is formed with a cylindrical projection that fits within a complementary recess on the ring to center the ring on the holding elements, and it is possible as in U.S. Pat. No. 4,653,304 to provide a morse-taper type of conical interfit to spread the cylindrical part and thereby tighten it in the wear ring. In other arrangements, for example in German No. 1,602,086, frustoconical formations are used to center the ring on the holding elements. When such formations are used there is a problem of metal fatigue in the roll ring. The axial compression necessary to rotationally couple and center the ring must be excessive and normally has a substantial radial component that stretches and that can damage this ring.